We have been investigating the localization, stability and metabolism of the motility related organelles, microfilaments and microtubules, in normal and virally transformed tissue culture cells. We propose to investigate the possible differences in the ability to polymerize the constituent proteins of these organelles as the result of viral transformation. To date, we have discovered that the important contractile protein actin is altered in total content in normal cells as they approach confluency, whereas the transformed cells do not respond to intercellular contact by altering the amount of this protein. The total protein within the normal and transformed cells also shows a similar difference in quantity per cell in the normal cells as they begin contact and similar lack of response is noted in the transformant. Future studies will investigate the turnover and stability of these proteins and their constituent organelles in normal and transformed cells.